1. Field of the Invention
The present invention relates to a video signal display system, a video signal reproducing apparatus, and a video signal display method for displaying an interlaced video signal as if it were a progressive video signal on a display apparatus capable of displaying a progressive video signal.
2. Description of the Related Art
Video signal formats are classified into an interlace format based on interlace scanning and a progressive format based on progressive scanning.
The interlace scanning is a format in which a single video screen is formed of scan lines and every other scan line thereof is skipped. In this format, when the scan of every other scan line in a single screen is completed, the skipped scan lines are then sequentially scanned. Performing interlace scanning twice therefore produces a single display screen (single frame). That is, a single frame includes two screens, first and second fields in each of which every other scan line is skipped.
On the other hand, in the progressive scanning, no scan line is skipped, but the scan lines are sequentially scanned one by one.
Interlaced video signals are typically used in television broadcast (in digital television broadcast, however, progressive video signals are used in some cases).
To display an interlaced video signal on a video signal display apparatus capable of displaying only progressive video signals, the interlaced video signal needs to be converted into a progressive video signal.
To convert an interlaced video signal into a progressive video signal, for example, motions in the preceding and following images are analyzed to complement the skipped scan lines. In an image obtained by converting the interlace format into the progressive format (hereinafter referred to as IP conversion), however, combining two fields causes a moving portion to be unsharpened (hereinafter referred to as a motion blur).
To eliminate the motion blur generated by IP conversion, for example, a progressive video signal is displayed as if it were an interlaced video signal. That is, IP-converting an interlaced video signal and then handling the converted progressive signal as if it were an interlaced video signal allow a video signal display apparatus capable of displaying only progressive video signals to display the converted progressive signal with no motion blur. An example of a method for displaying a progressive video signal as if it were an interlaced video signal involves dividing a single frame in a progressive signal into two fields, inserting black odd-numbered lines in one of the fields, and inserting black even-numbered lines in the other one of the fields. Handling a progressive video signal as if it were an interlaced video signal this way is hereinafter referred to as pseudo-interlacing, and a pseudo-interlaced video signal is called a pseudo-interlaced signal.